There is a seatbelt device in which a webbing is divided in two in a length direction and a bag body is provided at a location between the divided webbing. When there is a vehicle collision, gas is supplied to the bag body and the bag body inflates and expands at the front side of the body of a vehicle occupant. A portion of the bag body of this seatbelt device at the side of the bag body at which the occupant is disposed and a portion of the bag body at an opposite side from the occupant are joined by a tether. An inflated shape and the like of the bag body are controlled by the tether (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2013-28241).
Between the webbing that is divided in two, only the bag body is subjected to tension applied from the webbing. Therefore, in a state in which a pretensioner device, a force limiter mechanism or the like structuring the seatbelt device is activated, the bag body is stretched or compressed in accordance with increases and reductions in tension applied to the webbing. This causes variations in tension in the webbing. Thus, the tension of the webbing may not be stable.